This morning we found almost a dozen Black Swallowtail caterpillers munching on the fennel in our vegetable garden.  We carefully plucked them off the fennel and placed them on the Golden and Heart-leaf Alexanders (Zizia) in the flower garden.  All three plants are in the carrot family (Apiaceae) and are food for the black swallowtails.  Later this afternoon, most were spotted chomping away at the Zizia.  We will keep an eye out in the coming days for chrysallises.